A rotary actuator (hereinafter referred to as “actuator”) as a mechanism to convert input energy into physical rotation force is used in various types of industrial machinery, for example, as a power source of movable mechanism in an ATM device (automatic teller apparatus), printer device, copying machine, facsimile apparatus, or the like.
For the mechanism of the actuator, a mechanism is generally known which uses electromagnetic force as a power source and causes an output shaft to make reciprocating rotary motion (hereinafter referred to as “oscillation”) with a predetermined rotary angle. As an example, the applicant of this application has already disclosed this type of mechanism in Patent Document 1.
In the configuration of the actuator according to that application, two magnetic coils having a magnetic core at their center are oppositely laid and spaced with each other, and a permanent magnet is arranged between the magnetic coils with an air gap. The permanent magnet is held by a rotor supported in a cantilevered manner by an output shaft, and is oscillated by the attraction or repulsion to the permanent magnet according to switching of the electromagnetic coil poles, thereby providing an output as a driving force.
Further, as another configuration example, there is an actuator disclosed by Patent Document 2 (rotary solenoid). In that configuration, it is provided with a shaft portion rotatably held by a casing, a movable portion whose one end fixes to the shaft portion and the other end holds a magnet, and a pair of magnetic coils arranged at both sides of the movable portion.
The actuator of the above configuration arranges therein a stopper in the casing that limits a movement of the rotor. The stopper can be a cause of vibration and noise due to contact or collision of the rotor. Accordingly, a shock-absorbing member that has anti-vibration or vibration absorbing properties covers the stopper, or the stopper itself is made of a shock-absorbing member.